Broach



P 1950 K. REINHARD 2,521,747

BROACH Filed 1945 2 Sheets-Sheet 2 I IV VENTOR. /(a r/ A e/Wham Patented Sept. 12, 1950 KarlIReinhard, New -Ybrk;N. Y

Application Octobcri16, 1945,1Srial-No. 622,663.

(Grantedv-iinder -thc=:act of March. 3,;. 1 883,; as;

amended April 30, 1928;. 370: G. 757) 4 Claims? This invention relatesflin generaLtoa. method" forproviding elongated holes and in particular touai broach an'dxa broachingoperati'on.

Ins-the construction ofcertain articles such as,-;

for-example, gun parts andthe like, itis frer quently; necessary: to. provideelongated holes. in

brittle: castings. Many gun parts. are manufactured of cast brass and similar brittle'materialsxwhich are not capable: otzwithstanding e a punching -.operation, andllsomei iof i thesei castings;

are provid'ed with elongatediholes; Intheseirr stances it has beencustomary to: resort toomae chining operations. whichaare: costly and..:. in, efficient;

It.is an object' ofithisiinventionitoaprnvidc a: method and apparatus for making elongated:

holes in brittle materialse.

It is another object ofithis inventiontoprovi'dee a breach for. making: elongated: holes in brittle:

mate rials: i

It is an additional object ofthiseinrventiori tots provide a method of broachingiiz long'atediholes in brittle cast materials.

Further objects and advantages iofithisi invent tion; as well 1 as: its: construction, arrangement and operation, will; bei apparent flOll'l'i th role:

lowing description andnclaimssin connectioniwithz the:accompanyingdrawings; in which;

Fig; 1 is across-sectional. elevation of the? deviceoi: the invention,.taken on \line: -4 of:

Fig. 2, M

Fig: 2 1513, front elevation of. thezappar'a'tus shown in Fig. 1,

Fig. 3: is a perspective. of theibroaching to'oli embodied vin" the: invention,

Fig. 4 is a perspective of a work piecesuitazble fort practice of: the invention, .manufacture. of

the shown work piece having been completed to have been exaggerated to illustrate them more 1 clearly.

There is shown in Figs: 1' and 2" a; fixture, generally designated I0 that" operates t'o-liold a; work piece 14 for machining-by the t'ool Hf;

Tool H is a broaching' tool; and is adaptedto be operatedina punch press which may be of conventional construction. Accordingly, the

fixturev Hi iszpositioned inthe punch press,;-,for.:

exampleaby. being fastenedto thesurface otzthet' conventional punchpress platen. Thefixtureds. preferably. raised from the surface of the,;platerr,;.

f or example by being .restedon spacer blocks. not shown; thus to; provide clearance-under the: fiX-.-- tureiforchips to fall onto and through the; punchpress; platen not shown, and-also to, provide clearance for the tool: i-iin'its. cutting stroke.

The-tool H is attached,to'thezitoolholder 12; of the machine by any suitable means, suchas. the screws l3; Fig. 2, thegshankiend 46 ofcthew toolai M being formed to.- any suitablecontour; that. adapts it to the tool holder I2 of the particular" punch press in which the. fixture; ll1-- of thezin vention is to be used.

The fixture lilcomprises the workeholding, plate IS, in the form of a surface plate, on which thezwork piece-i4 is positioned. The leven 16-, mounted pivotally at Hiton the; spacer mernecn I1, Fig. 2; is manually operable. to. clamp} the: workpiece M in position on the plate I 5;-

The locating pin 22 is mounted to slide in-the bore through the surface plate 55, andtOi'pI'Or jectiinto thebore in the bosstipof-the-work pieces I43 the zlocatingpin-22 thus'pperating to, center thework piece 14 in the; jig 0. The. surface,

plate 15 is slotted at 240; to'receive the-key 24,.

that is fastened in the slot 24min any; suitable manner, for example by means of the screw 241).

See. Fig. '7. The key 24* engages-the keyway 2'5 The bracket 21 isattached tothe bottom sur face of the plate 15,103; means of the screws=2|:a,. for example. The bracket 2!. is slotted atza tol contain the: lever 20, pivoted at 48 to move up,

and down in' theslot 23. The lever 20 is proiected throughthe locating pin 22', and is atev tachedlthereto by, means of the pivot; pin 4|.

Tension springs l9? operate: to raise -the lever. '20,,

and hold itin' its raised position shown in Figs.

1 and 2:. This projects thewlocati-ng pin 22rinto the boreof: the work piece l4.- The:leveririilnim,

provided with the handle 42 for manually d,e pressing it to remove the pin 22 out of the. bore: of:.thework piece l4;

A suitable work piece M for practice of the:

invention is illustrated in Figs: 4; 5 and, 6-.- It: comprises, for example; the boss" 3 I; that is bored,

the; pin 27.."- of the. lie being;v adapted tozfit; the i That-piece comprises the:v wings 30, and these are provided with elongatedix holes 32, Fig. 6, for example for attachment of the piece when it is assembled into a component or unit.

The purpose of the present invention is to machine the elongated holes 32.

Preparatory to the broaching operation, the holes 29 are drilled in the wings 30, diameter of the holes 29 preferably conforming with the width of the slots 32, and th holes 29 being located in the wings 30 to form the rounded ends of the slots 32.

The width of the broaching tool ll conforms with the width of the slots 32, and one edge 45 of the tool is rounded semi-circular, the radius of the half-round 45 preferably conforming with the radius of the holes 29. 21 of the tool ll extend away from the half- .round edge 45 thereof along the sides and opposite edge of the tool as shown. The end of the .tool II is provided with the pilot pin 28, the diameterof which preferably conforms with the diameter of the holes IS in the piece. The -circle of the pin 28 coincides with the arc of the half-round edge 45, as shown in Fig. 3. r

The cutting teeth 21 of the tool are stepped :as shown in Fig. 3, to progressively widen the tool away from the pilot pin 28 towards the shank end of the tool. Under preferred practice a shank 46 is provided that has a rectangular edge opposite the half-round edge 45, the width of the tool in the shank corresponding with the distance between centers of adjacent holes 29 plus the radius of the half-round 45. As previously noted, the teeth 21 are shown exaggerated,

in actual practice the teeth 21 being stepped in -v increments of approximately 0.010 in accordance with prior art practice of broaching tool design.

The jig I is provided with the tool guiding. plate 26, which is attached to the work holding.

The cutting teeth hearing to support the thrust of the cutting operation exerted widthwise 0f the tool.

Pursuant to practice of the invention, a job below. The piece is also oriented in the jig to .seat the keyway over the key 24, and the lever llS is swung to the position shown in the drawings 'to hold the piece 14 against the surface of the plate IS. The piece is nowready' for the first machining operation of the invention.

The tool H is in line with the outermost hole 129 of one of the wings and when the punch press is operated to descend the tool I I, the pilot pin 28 of the tool first enters the hole 29 in line with the tool. The cutting teeth 21 operate to rremove the material between the holes 29 of the given wing 30, forming the slot 32, and this continues until the shank 46 of the tool enters the The piece I4 is now in the condition illustrated in Fig. 5. When the tool H rises to its uppermost position, the lever [B is operated to release the piece, which is then rotated on the center of the pin 22, and the lever I6 is again operated to clamp the piece in the jig. The punch press is again operated to depress the tool II, and it now removes the material between the pair of holes 29 of the other wing 30. The piece I4 is then completed and in the condition illustrated in Fig. 6, with both elongated holes 32 machined.

It will be clear to persons skilled in th art that the device of the invention enables a dim-- cult machining operation to be performed quickly and at low cost.

It is obvious that a pair of broaches may be substituted for the single broach H shown in the figures. However, this has not been done at the present time because the use of a single broach insures that no workman need place his finger below the operating portions of the machine and Numerous other variations and modifications in the above described device will be obvious. to

those skilled in the art and it is to be understood that the scope of this invention is to be determined not by the specific illustrations given' liereinbefore, but on the contrary, the scope of the invention is to be determined by the apparent claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A broaching tool for elongated holes comprising a semi-cylindrical side wall, cutting edges extending peripherally of the tool embody-1 ing the remainder of the side walls beyond the semi-cylinder, the thickness of the tool equaling the diameter of the semi-cylinder, and the width of the tool varying progressively lengthwise thereof to a width greater than the diameter of the semi-cylinder.

2. In a tool as defined in claim 1, a cylindrical locating plug projecting from the narrower end of the tool, the plug having the same diameter as the semi-cylinder and being coextensive therewith.

3. Apparatus for producing an elongated hole in a casting comprising a punch-press including a tool holder, a broaching tool carried by the of the tool embodying the remainder of the side.

walls beyond the semi-cylinder, the thickness of the tool equaling the diameter of the semi-cylinder, and the width of the tool varying progressively lengthwise thereof to a width greater than the diameter of the semi-cylinder, a work holder operable to locate the casting in the punch-press in position for the hole to be formed.

KARL REINHARD.

It will be understood.

.(References on following page) REFERENCES CITED Number #1 2,050,901 .Lhe fOllOWlllg references are of record 1n the 2 165 977 file of this patent: 2'184383 UNITED STATES PATENTS 5 7 Number Name Date 150,909 Stewart May 12, 1874 Number 280,866 Ryan July 10, 1883 205,415

Name Date Sundell Aug. 11, 1936 Maxwell July 11, 1939 Glenny Dec. 26, 1939 LaPointe Jan. 8, 1946 FOREIGN PATENTS Country Date Great Britain Oct. 18, 1923 

